I figured I would release my own mod that slightly differs from the Retro Sounds Mod. This mod aims to completely replace all possible sounds with sounds from beta, and remove sounds that were not present prior to version 1.8.1, UNLESS those said sounds are for an entirely new object added after version 1.8.1.
An example: Swimming sounds will be removed because they were introduced after version 1.8.1, and water has always been present in Minecraft; where as say the Iron Golem will still have his sounds because he himself was introduced after version 1.8.1, this way you get the beta experience, but nothing is left without a sound, that is unless there was no sound for the object prior to version 1.8.1, such as the tool breaking sound (which scares the crap out of me anyway ).
This has been updated to work with the new texture locations in minecraft.jar, so any futher updating on my part should not be required! Nevertheless, I will try to keep an eye out on this page!
1. Download "Audiotori" at this link, and follow the instructions to set it up properly.
2. Extract the "Beta Sounds" folder to your "audiotori" folder in the Minecraft directory (if there is none, create one or launch Minecraft so one is created), Located at: C:\Users\YourUserName\AppData\Roaming\.minecraft
3. To enable these sounds in game, press F9 while playing and this will bring up "Audiotori", and enable the sound pack. Sometimes you will need to disable and re-enable it to get it working correctly.
Things to note:
If you wish to hear a sound that this mod is disabling, simply navigate to the Beta Sounds folder in the Audiotori folder and delete the sound you wish to hear (sounds are disabled by use of blank sound files).
The "Retro Sounds Pack" mod is my inspiration, here is this link to its forum page.
Also, if you want the original dirt menu with no panorama view, visit this link!
As an added bonus I will also be including a texture pack you can use to remove a few simple effects and textures that were not present in the beta prior to version 1.8.1. One effect being the moon shapes found in explosions, and the moon phases! To install simply extract the "Beta Mode" zip archive file into the "texturepacks" folder located within the Minecraft directory.
Update - 11/11/12
* Added beta textures for cobblestone, mossy cobblestone, gravel, iron blocks, dispensers, and monster spawners!
Update - 03/29/13
* Added support for the newer method that minecraft obtains textures